Cod sursa(job #206686)

Utilizator cata00Catalin Francu cata00 Data 8 septembrie 2008 20:28:14
Problema Secventa Scor 60
Compilator cpp Status done
Runda Arhiva de probleme Marime 1.61 kb
#include <stdio.h>
#include <string.h>
#define MAX 500010

int a[MAX], left[MAX], right[MAX];
int n, k;
int best_start, best_end, best_base;

void read(void) {
  FILE *f = fopen("secventa.in", "rt");
  fscanf(f, "%d %d", &n, &k);
  for (int i = 0; i < n; i++) {
    fscanf(f, "%d", &a[i]);
  }
  fclose(f);
}

void compute_right() {
  int sp = 0;
  int stack[MAX];

  for (int i = 0; i < n; i++) {
    while (sp && (a[i] < a[stack[sp - 1]])) {
      right[stack[sp - 1]] = i - stack[sp - 1] - 1;
      sp--;
    }
    stack[sp++] = i;
  }
  while (sp) {
    right[stack[sp - 1]] = n - stack[sp - 1] - 1;
    sp--;
  }
}

void compute_left() {
  int sp = 0;
  int stack[MAX];

  for (int i = n - 1; i >= 0; i--) {
    while (sp && (a[i] < a[stack[sp - 1]])) {
      left[stack[sp - 1]] = stack[sp - 1] - i - 1;
      sp--;
    }
    stack[sp++] = i;
  }
  while (sp) {
    right[stack[sp - 1]] = stack[sp - 1] - 1;
    sp--;
  }
}

void scan(void) {
  best_base = -1000000;

  for (int i = 0; i < n; i++) {
    if (left[i] + right[i] + 1 >= k) {
      int start = i - left[i];
      int end = start + k - 1;
      if ((a[i] > best_base) ||
          ((a[i] == best_base) &&
           (start <= best_start)) ||
          ((a[i] == best_base) &&
           (start == best_start) &&
           (end < best_end))) {
        best_base = a[i];
        best_start = start;
        best_end = end;
      }
    }
  }
}

void write() {
  FILE *f = fopen("secventa.out", "wt");
  fprintf(f, "%d %d %d\n", best_start + 1, best_end + 1, best_base);
  fclose(f);
}

int main() {
  read();
  compute_right();
  compute_left();
  scan();
  write();
  return 0;
}